The present invention relates generally to down-the-hole drill (DHD) hammers. In particular, the present invention relates to a DHD hammer having a roller ramp clutch and coupler to simultaneously rotate a piston and drill bit.
Typical DHD hammers involve a combination of percussive and rotational movement of the drill bit to drill or chip away at rock. Such DHD hammers are powered by a rotatable drill string attached to a drilling platform that supplies rotation and high pressure gases (e.g., air) for percussive drilling. Moreover, in percussive drilling, rock cutting is a result of percussive impact forces rather than shear forces. In other words, rotation of the DHD hammer serves to rotationally index the drill bit to fresh rock formations after the drill bit impacts a rock surface rather than to impart shear cutting forces to the rock surface.